Train control



Sept. 13, 1932. c. s. BusHNELL.

TRAIN CONTROL 4 Sheets-Sheet l Filed March 9. 1922 :25mm/vbo@ z v 1 Sept- 13,'.1932- vc. s. BusHNELl. 1,877,553

TRAIN CONTROL Filed March 9. 1922 4 sheets-sheet 2 l Fl 6.3.'

Svpca 13, gSZ. c. s.. BUSHNELL TRAIN CONTROL Filed March 9. 1922 4 Sheets-Sheet 3 TToRNE Y.

Sept. 13, 1932. Y c. Ls. Busi-:NELL 1,877,553

TRAIN CONTROL Filed March 9. 1922 4 Sheets-Sheet4 "4 Patented Sept. 13, 1932 UNITED sarna ,ATI-:Nr oFFicE i CHARLES S. BUSHNELL, O ROCHESTER, YORK, ASSAIGN OR TOGENERAL RAILWAY SIGNAL COMPANY,` OF GATES, NEV YORK, A. CORPORATION OF NEW YORK TRAIN conrnor.

Application filed MaglfchkS, i922. Serial No.4542,270.

This invention relates to automatic train control systems for railroads, and more par-y ticularly to that part of such systems which involves the transmission or communication of control impulses or influences from the trackway to moving vehicles.

One of the essential elements of any type or' automatic train control system is an etticient and reliable means for communicating or transferring suitable control impulses or influences from the trackway to a moving locomotive or other vehicle under the unfavorable conditions of high speed, exposure to weather, close clearances, and the like, found in practice. On account of the diiiicult con-k ditions to be satisfied, it is considered desirable to communicate such control influences through an intervening space or air gap between parts on the track and `parts on the vehicle, rather than by direct mechanical cooperation or physical contact. The principle of magnetic or electro-magnetic induction is, it is believed, especially adapted for Y this purpose.

In connection with suoli an inductive system, it is thoughtl to be preferable, for various reasons, to use a track device which does not Vrequire the supply of electrical energy Y y from the trackway` while in either the active 3cor inactive condition. Such a track device, in the interests of safety, must also be of such a character that so :tar as practicable, any Vtailure of circuits or contacts, breakdown of insulation and other defects at all likely to occur in practice, should be on the side of safety, that is, cause the track device to pro-V duce a stopping control. Further, in order to avoid false operation and delays, the nai ture of the track device should be such that the trackway, more particularly the track- .rails of switches and crossings, and similar magnetic bodies.

To meet these various re uisites it is ro-k posed in accordance with the present invention, to produce the desired control influence Y. by the action of a magnetic fieldv existingy von the track under dangerous traffic conditions source of flux which cooperates with a generating or inductingtrack element to produce inthe latter a current, by providing another transmitting or'V sending track element, to which this current is conducted under dangerous tratlic conditions, and which acts to create a magnetic field adapted to cooperate with a iuX responsive receiving element on the car,.the response of the receiving element and associated devices being utilized to exert the desired control of the vehicle.` In this particular embodiment of the invention, the trackway equipment, comprising the generating or inducting element and the sending or'transmitting element, is put inthe inactive or non-stopping condition, kcorresponding to clear traiiic conditions, bybreaking or sto pingy the transmission of current between t e generating element and the sending element,

preferably by placing a shunt ot lowy resist! ln the type, of ,iniiuence communicatingv means just outlined, it will be evident that the field or primary element on the vehicle will tend tomagnetize switchj points, track rails of crossings, and 'similar iron bodies along the track inpassing over them and under unfavorable conditions, theresidual flux of such iron bodies, if properly vdisposed' or located, will produce upon the receiving element on the vehicle an effect of the vsame nature as that of the sending element on the track. In other words, the residual magnet-A ism in track rails and thelike, will tendtov causepremature or false operation of the car equipment. To .obviate the possibility of such interference with .the desired operation by magnetized rails or the like, it is contemplated that the two pairs of cooperating elements on the track and on the vehicle will be disposed in a different relation with respect to the track rails, so that any residual magnetism on the track created by the field element on the vehicle will be unable to aii'ect the receiving element on the vehicle, while at the same time the track sending element will be in such position to cooperate effectively with saidveliicle carried receivingelement.

In the typical embodiment of the invention above described, it will be observed that the transmission of the desired controlling iniiuences is dependentk lupon integrity of the coilsV or windings of the generating and sending elements on the track, and the electrical connections between these elements over which the induced currentV is conducted; and while the parts of these circuits can be carefully constructed with ample margin in strength and insulating qualities, so that a breakdown is no more likely to occur than in any other mechanical structure, it is proposed to ,provide a scheme of automatically checking up the performance of these circuits, and in case defect is detected, to automatically govern train movements on the side of safety. Generally speaking, this scheme of checking or detecting failure Yconsists in` sendingrcurrent through the coils and wires on which the safety of the system depends, and in case of defect, to obviate the possibility of accident on account 0f such defect by arresting or .slowing downy each train at the next control point in the rear, thereby assuring that such train will not run into any train that may be directly ahead of the defective track devices and depend on them for protection. Another characteristic ofV this automatic checking-scheme is that as soon as a Vfailure or defect exists,.each train will be slowed down or stopped at a point inl the rear until things arefiXed.

The various particular objects and characteristic features of the invention will be iny part apparent from the foregoing discussion, and will appear as the detailed description progresses.

YIn describing the invention in detail, reference will be made to the accompanying drawings, in which Fig. l shows diagramniatically and in a simplified manner one form of the track devices and circuits constituting one embodir ment ofthe invention;

Fig. 2 shows diagrammatically one form of the car equipment and the manner of cooperation of the car-carried and trackway tion Fig. t illustrates a modified form of av car-carried apparatus in which the thermionic amplifier has been omitted;

Fig. 5 illustrates another modified form of car-carried apparatus in which the receiving element directly actuates contacts carried thereby;`

Fig. 6 illustrates a modified form of carcarried apparatus of the type shown in Fig. 5

Fig. 7 illustrates a modified form of field element in connection with the car-carried system illustrated in Fig. 4t;

Fig. 7 -A is a curve of induced voltage obtained by the car apparatus of Fig. 7; and

Fig. 8 to 17 illustrate diagrammatically various ways in which the generating track element and the sending track element may 'be located with respect to each other and with respect to thetrackway. Y

Various arrangements of trackway circuits for controlling the condition of the trackway devices may be employed, and in the accompanying drawings there is shown only one typical arrangement. Referring to Fig.f 1, tlietrack rails l are divided by insulated joints 2 into blocks in the usual way,

one block I and the adjacent ends of two other blocks H and J being shown. Since the parts associated with the various blocks are the same, for convenience they will be given like reference characters with distinctive exponents. Each of the blocks is provided with .a track battery 3 and a track relay l in the 4same way as in the ordinary block signal systems.

Since it is contemplated that a train controlsystem should preferably be an adjunct to a block signaling system, rather than as a substitute for such a system, the usual fixed trackway signals are shown in connection with the train control system of this invention. As a typical illustration, one particular form of asemaphore signa-l has been illustrated conventionally, namely, a three-position with neutral line relay control. It

y should, however, be understood that any other form of tliree-position signals, or two-position signals, may be employed equally as well. rIhis signal S has been shown diagraininatically because its specific construction is no part of the present invention, and may be any one of the well-known formsl in common use. In the ltypical semaphore signal, the semaphore arm of the signal S is biased by its own weight to the horizontal or stop position, conveniently called-the Zero degree position; The specific mechanism -fo'r operating the signal has not been illustrated because it is no.

part of the present invention; but in general this mechanism vcomprises a motor, gearing, hold clear device, and .automatic circuit controllers, all organized so as to cause the semaphore blade to berdriven in opposition to its bias to an inclined, caution, or 45 degree position andheld there, or still further driven to a vertical, clear or 90 degree position, these movements being obtained by supplyingcur.- rent to a caution or 45 degree control circuit to actuate it to said first or caution position, and by supplying current to a 90 degree control circuit to actuate it to its 90 degree or clear position shown in Fig. 1 of the drawings. These control circuits are shown dia-V grammatically as leading' to the semaphore blade itself, and the position at any time through the various steps of the operation of the device may be determined by observing whether current is being supplied to the 45 degree control circuit, which would bring the semaphore to the 45 degree position, or if current is supplied to both the 45 degree circuit and the 90 degree circuit, which would bring the semaphore to its clear or 90 degree position, or if both of these circuits are deenergized, which would cause the semaphore to assume the zero degree -or danger position.

In Fig. 1 of the drawings are shown diagrammatically three independent circuit controllers, which in practice would usually coinprise a single controller drum having three independent controller segments and stations ary Contact fingers therefor. One of these circuit controllers will for convenience be called the checking circuit controller, and comprises a stationary segment 5 which will be in contact with a movable circuit controller arm 6 between Zero and degrees, where m represents an angle of something less than 45 degrees. Another circuit controller, whichl will be termed the clearing circuit controller, comprises a segment 7 which will be contacted by a. circuit controller .arm 8 between as and 90` degrees. A third circuit controller, which will be termed the line circuit controller, comprises a segment 9 which will be contacted by a contact arm 10 substantially between the 45 degree and 90 degree position. In the diagrammatic illustration of the circuit controllers, the movable arm will in each instance be parallel to the semaphore blade, and as illustrated in Fig. V1, the semaphore blade and each of these arms is in its 90 degree or clear position.

Each of the blocks vis provided with a line relay 11, and while polarized line circuits or any other well-known expedient for controlling the cautionary or distant indication may be employed,- in the particular construction illustrated a neutral line relay is used, the energizing circuit for the line relay of vblock I being as follows Starting from the terminal P of a battery, segment 91 and contact arm 101 of the line circuit controller of signal S1, wire 121, front contact 181 of track relay 41, line wire 141, front contact 15 of track relay 4 of block I, wire 16, winding of the line re-r lay 11, to thecommon return wire. A

t the entrance vof each block is located a pair of track elements, one of which is shown mounted crosswise of the track adjacent the ment L. A short distance in the rear of this i generating orvinduction element L is another similar element located lengthwise of the trackway, which will be referred to as a sending or transmitting element T. These track elements L and T each comprise a U-shaped soft iron core, preferably laminated to reduce the harmful eifects of eddy currents, the upstandingv legs, being provided with enlarged pole pieces, and each having thereon a coil or winding 17. The coils 17 of each track element L and T are wound and connected in a manner so that the voltages induced in these coils due to a change of flux in the core thereof will be cumulative.

The coils 17 of the induction'element L and the transmittingA element T are connected in a'closed or loop circuit.V Since the transmission of a controlling influence by these track elements is dependent upon the integrity of this loop circuit, it is contemplated that this circuit will be made up in practice of wires of large size, preferably stranded, well insulated and armoured, for the purpose of reducing the possibility of failure of this circuit. To'further safeguard this loop circuit against weather, insects and tampering, the wires arev preferably housed in a conduit and made as short as practicable. Y

Although this loop circuit can, it is believed, be made as dependable as any mechanical mechanism by care in design and construction, it is proposed to provide, as an additional safeguard against failure of the train control system by accidental breakage or injury to the wires of this circuit, a scheine or system for automatically checking up they integrity of this loop circuit at each train movement, and in case of failure cause automatic control of following trains on the side of safety. For this purpose checking relays 18 and 19 are employed. These check relays are illustrated conventionally; but they should be designed with operating charactei istics to especially adapt them for their purpose by making their impedance as -low as possible, and preferably by providing balanced moving elmentsto prevent their actuation due to vibration of passing trains to which they will be subjected. Two check relays 18 and 19 are preferably used, because ics iis

the checking current throughthis loop ciri cuitfcan then be passed through the two halves of the circuit in multiple and without providing switches in this circuit, that is, by passing a currentfrom one side of the closed loop to the-other side ofthe same in a manner so that each branch of the circuit passes through a check relay.

For the purpose of understanding the operation and utility vof the devices illustratedY in Fig. 1,'the operation thereof will be presently explained; but in vorder to understand. the purpose of the track elements, the car-cai'- ried devices which coact therewith will be briefly referred to. Generally stated, the car-carried apparatus comprises a pair of car elements very similar to the generating and sending track elements. One of these car elements, which will'be known as the'tield l or primary element F, is located on the vehicle crosswise of the track in cooperative relation to the generating or induction element L. This field element F is normally energized by a direct current roducing a constant field of flux emanating in the direction of the track element. The other car-carried detecting or receiving element D is mounted lengthwise of the vehicle so as to be in cooperative relatonship with the sending or transmitting element T at the time when the field element F is in cooperative relation with the :induction element L. This detecting element D is provided with flux responsive means adapted to control the train in any suitable manner. Thus, when the eld or primary element F passes over the generator or induction element L, a momentary current will liow in the loop circuit, thus producing a variable magnetic iield in the transmitting element T, which in turn produces a momentary change of liuX in the flux responsive means of the receiving or detecting element D.

pemtc'mt of Fig. 1.-Assuming that no trains are present in blocks I or J, the position of the various devices and the condition of the various circuits in Fig. 1 will be normal, as illustrated in the drawings. The operation of the parts and circuits associated with each block are the same, so that a description of this operation in connection with the block l will apply to the other blocks and will show how train movementsare governed automatically on all parts of the railroad equipped.

The coils 17 of the track elements L and T are connected together in the loop circuit hereinbefore mentioned, this circuit as shown in Fig. 1 being traced as follows :--Commencing at the upper coil 17 of the track element L, wires 2O and 21, checking relay 18, wire 22, coil 17 of tra-ck element T, wires 23 and 24, other coil of said' element T, wire 25, other checking relay 19, wires-26 and 27, other coil 17 of element L, and wires 28 and 29,.

In the specilic type of vblock signal system illustrated, the several signals S are maintainedl in the vertical or clear position normally, that is, when no trains are present. The control circuits for these signals are the same, and a description of those associated with signal S at the entrance to block I will suliice for all; For the purpose vof simplicity, these control circuits for the signals,

and also the circuits associated with and govn to opposite terminals of a battery or other i source of current, it being understood that these respective circuits are connected to different batteries of theV proper voltage, or wholly or in part to the same battery in conformity with recognized practice.

The circuit which supplies current to the operating mechanism of signal S and serves to maintain that signal in its normal clear position, conveniently termed the 9() degree control circuit, may be traced on the drawings as follows z-Commencing at P, circuit controller 7 8, wires 30 and 31, front contact 32 of track relay 4, wires 33 and 34, front contact 35 of line relay 11, wire 36 to the signal mechanism (not shown), and thence to N.

The circuit for holding the semaphore signal Sin the inclined or caution position, conveniently called the 45 degree control circuit, may be traced in the drawings as follows Commencing at P, circuit controller 7-8, wires 8O and 81, front contact 32, and wires 33 and 87 to the signal mechanism and thence to N.

Under clear tra'llic conditions, that is, when no train is present in either of the blocks I or J, the coils 17 of the track element L at Ventrance to block I are shunted by a clear or proceed governing circuit of low resistance, comprising wires 38 and 39 and front contact 40 of line relay 11, so that with said line relay picked up, the coils 17 of the track element L are included in a closed circuit of lov.T resistance, the complete circuit being traced as follows Commencing at the upper coil 17, wires 20 and 38, front contact 40, wires 39 and 27, other coil 17 wires 28 and 29.

Assume that a train is in the block H moving in the direction of the arrow. As this train advances into the block T, the track relay 4 will be robbed of its energizing current, causing its four front contacts to open. The opening of front Contact lzcauses the line relay 11 to be deenergized, thereby opening its front contact 40 and in turn opening the low resistance shunting circuit around the Vcoils 17 of the generating element L. This places the track elements L and T in their active stopping condition to transmit a stopping influence to a passing train in the manner more fully explained hereinafter.

The opening of the front contact 82 of the track relay 4 opens both the 45 degree and the degree control circuits of the semaphore signal S, thus causing the semaphore arm of the signal S to gravitate to the zero degree or danger position, consequently interrupting the circuit at the clearing circuit controller.

Assumenowthat the train proceeds into.

the block J. The track relay 41 is deenergized, thereby opening its front contacts and putting the signal S1 to stop inthe saine manner as heretofore explained With respect to the block I. Either the opening of front contact 18l or of the line circuit controller actuated by the semaphore signal S1 interupts the line circuit to the line relay 11 at the entrance of block I. When the train in question passes out of the block I, the track relay 4 is again energized, thereby closing its four front contacts.

The closur-e of front contact 41 completes the checking circuit which may be traced as follows Starting at the terminal P of the battery, checking circuit controller 5 6, Wire 42, front contact 41 of track relay 4, Wires 43 and 28, one coil 17 of the induction element L, Wires^27 and 26, Winding of check relay 19, Wire 25, one coil of transmitting element T, and Wires 24 and 44 to the terminal N of the battery; and another circuit portion in multiple With this lattercircuit starting at Wire 29, through the other coil 17 of the induction element L, Wires 2O and 21, Winding of the check relay 18, Wire 22, through the other coil of the transmitting track element T, and Wires 24 and 44 to the terminal N of the battery.

If both of these checking circuits are intact both of the checking relays 18 and 19 Will be energized, thus completing the following circuit for initiating the clearing of the semaphore arm of the signal S to its 45 degree position; rIhis circuit may be traced as follows From the terminal P of the battery, front contact 45 of check relay 18, Wire 46, front contact 47 of other check relay 19, Wire 48, Wire 81, front contact 32 of trackrelay, and thence as in the 45 degree control circuit of the signal S, hereinbefore traced.

During the movement of the signal arm toward its 45 degree position, its initial clearing or operating circuit Will be interrupted when the signal arm arrives at the angle a' (say 8 5 degrees), because the checking circuit will be interrupted by the checking circuit controller 5 6, and this in turn causes i the checking relays 18 and 19 to drop andV open the initial clearing circuit for signal S at their front contacts 45 and 47. When the semaphore of signal S reaches this 35 degree position. or slightly before that position, if desired, the clearing circuit controller 7 8 is closed, lwhereupon the regular 45 degree control circuit hereinbefore tracedis established and the semaphore is operated inthe usual Way up to its 45 degree position and held there, it being remembered that a train has been assumed to be in the block J, so that the signal can not be operated to its degree position, because the line circuit for line relay 11 is broken both at the contacts 131 of the track relay 41 and also at the circuit controller 1 101.

Assume now that the train in question hasv continued to move in the same direct-ion and passes out of the block J, the track relay 41 Will again be energized and its front contacts closed,thereby actuating the semaphore arm of the signal S1 to its 45 degree position in thc same manner as heretofore explained in connection With the signal S at the entrance of the block I. Under these conditions the line circuit controller of the signal S1 is in its closed position, and the line circuit tovr the line relay adjacent the entrance of the block I Will again be energized, thus causing the semaphore signal S to be actuated to its 90 degree position.

It is thus seen that during the passage of each train Vthe continuity of the loop circuit connecting the induction element L With the sending element T will be checked, and if this loop circuit should be open at any point in either of the branches of the checking circuits, one or the other of the checking relays 18 or 19 would not be energized; and therefore the semaphore signal S adjacent Y.the'rey to can not again assume its caution `or its clear position, because the current necessary,lv to start the semaphore from its zero degree position must pass through the 'front contacts 45 and 47 of both of thel checking rei lays; and if one or the other of these relays is deenergized, this lcircuitWill be open. InV

this event, since the semaphore signal at the entrance of the block Ican lnot assume any other than its danger position, although the track relay of this blockfmay be picked up, the line circuit to the vline relay at the entrance of the block II will be open at the line circuit kcontrollerv of the block I; andv therefore the signal at the entrance of the block I-I Will assume its caution position and open the Vshunting circuit around the correesA L sponding generating track element, thus put-1v ting the track elements of theV block H in theirroperative condition and slowing down or stopping each train coming into the block H until the damaged or interrupted loop circuitof the track elements of the block I has been repaired. In other Words, the in- Y tegrityrof this loop'circuit is checked each time a trainpasses, and unless the loop circuit is intact and in the proper conditiony to protect that train, the next following train is automatically slowed-down or vstopped in the nextblock in the rear, and in passing the defective track elements and entering their block, this following train must pass a danger signal' and proceed'pin accordance with the rules and 'regulations commonly enforced. In short, in case of breakage or in- `iury of the loop circuit at any time, each train is automatically compelled to stop or reduceV speed, perhaps'sooner than necessary, before it can reach a train that would other- Wise be protected bythe defective track elements. It Will be-observed that this checking Voperation is done when needed,lthat is, When a -train'passes and requires protection; and consequently, While the loop circuit in question might conceivably break doivn at.

fany time, vit is really not necessary, in a sense, to do` anything until the track elements in question aie needed to protect a train.

Also, it will be noted that the checking operation does not take place until the rear lend vof the passing train has cleared the corresponding block. For example, the checking of the loop circuit for the track elements L and T does not take place until the train has passed out of block I. For

'sthis reason the checking systemmay be said to performV the desired function at the time it is likely-to be most needed, that is, after thepassage of a train that may, on account of dragging equipment or its vibration, cause 2othe breaking dovvn of the loop circuit.

It is noted here that the arrangement above described for automatically checking up the integrity of the loop circuit for the track elements L and T, and governing trains on the fside' of safety in case of failure of such circuit, is not limited in its application to the automaticdetection of'failure of this particular circuit in a system of the specific type described; and it should be understood that 3mthis automatic' checking arrangement is susceptible, by'nierely making simplechanges in circuit connections, of adaptation to the detection of failure of any ycircuit in a train control or blocksignalsystem. 353-" Structure of Fig.-Q.-In Fig. 2 has been illustrated ina simplilied manner one arrangement of devices and circuits whereby a controlling influence may be received from the track devices illustrated in Fig. 1; and for 4?thepurpose of Vsimplifying the description, the most essential parts of the track devices only'have been shown.l

VVarious types of-cab signaling or brake control apparatus may be controlled by these bontrolling influences; and-since the particular character of this apparatus forms no part of the present invention,.and is not material to operation of the invention,-a simple type of train control device K hais been illusn-tratedfin the form of an electro-pneumaticr valve Whichvmay be used to vent thetrain pipe directly, and shut offthe-powerin any siutable manner,or Which may be usedr to controlother train control devices Which may be governed by the speed of the train, the pressure in'the brake pipe, the position-of the train in the block, and other factors enteringv into the desired control of the train. rlhis device K is assumed .to be provided With an iair valve having stick features, that is, one that has been designed to remain open after it has once been openeduntil a certain pressure reduction has been made. On account of this stick feature, the desired prolongation of-action may beI obtained even though the infiuence and opening of the relay Ris only deeiiergized, Will remain open and vent the -f train pipe or associated part of the air brake system, until the desired reduction in pres-v sure has been made to cause an eective brake application, whereupon the valve is automaticallyv reseated. that such an electro-pnuematic valve to constitute a suitable train control device has been selected to illustrate the nature and mode of operation of the present invention in its simplest aspect, and that the invention is not restricted inits luse to the control of such a valve, but may be advantageously employed for controlling the operation of any suitable train governing mechanism.

This train control device K may be actuated by a controlling influence directly, but it is preferably controlled by a control relay R which has been illustrated as governed in turn by a Well-known thermionic amplifier or audion shovvn diagrammatically. This auvdion has the filament 50, grid 51, and plate 52.

The influence receiving devices of the train control apparatus illustrated comprises a field or primary car element F disposed crosswise of the vehicle and in cooperative relation with the generating or induction element L` at the same time When the receiving or detecting car element D is disposed over the sending or transmitting track element T.

This field or primary element F comprisesv a U-shaped core of magnetic material, preferably laminated, having enlarged pole pieces and provided With coils 53 on each upstanding portion of the U-shaped core, these coils 53 being Wound and connected so that a current iovving therethrough Will set up magneto-motive-force in the core in the same direction. The coils of the field or primary car element F have been illustrated as being energized by the batteries B and C and connected in series to the train control device K and the front contact 54 of the controlrelay R.y

The receiving or detecting element D com prises a similar core or yoke provided with It should be understood secondary coils 55 which are Wound and con- Y nected in series in a manner so that a change between control points and is not under the influence of the track elem-ents L and T, the parts and circuits of the car equipment are in the condition shown in Fig. 2. The filament 50 is heated to incandescence by current from the batteiy A. The battery B will send a small amount of current through the coils 55 of the detecting car element D producing a certain potential on the grid 5l of the audion. This lpotential on the grid 5l of the audion causes a reduction in the plate circuit resistance, thereby causing a plate current of sufficient strengthto flow through the control relay R which will close its front contact 54. The'coils 53 of' the fieldor primary car element F being energized from the batteries B nd C create a downwardly projected field of Assume that a car with the carfcarried apparatus in normal conditions approaches the track elements L and T, and that the line relay ll (see Fig. 2) Vis deenergized, therebyr opening the shunt-ing circuity around the coils 17 of the induction track element L. As the car passes over these track elements in this stopping condition, asudden change of flux will take place in the induction track Yelement L, due to the passing of the strong magnetic field produced by the car-carried field or primary element F, thus causing the generation of one cycle of alternating in the coils 17 of the inductionxelement L, and

establishing a flow ofcurrent` through theV coils ofthe sending or transmitting element T.v SinceV the receiving or detect-ingerircarried element D is positioned directly over t-he sending Yor transmitting element T at this time, an rFalt/LF. will be induced in the coils 55 of the said receiving element. This E. M. F. generated in the coils 55 of the receiving element seems'to be also of a unicyclic nature, being first in on-e direction and then in the oppositeV direction. The coils 55 of the receiving element D are preferably connected to thebattery B ina manner so that the first portion of' this unicyclic El M. F. is ink an opposite `direction to the voltage of the battery B, thus reducing the potential on the grid 5l of the audion. thereby reducing the plate current sufiiciently to cause the control relay R to drop-its armature and deeiiergize the train controlV device K, which in turn applies the brakes or imposes some Votherforni of train control. y Y Y Assume now that the car-carried devices pass over the induction and transmitting track elements Lv and T with the shunting circuit about the induction ele-ment closed. Under these conditions no influence would be transmitted to the coils 55 of the receiving or detecting element vD, because the voltage" induced in the coils i7 of the generatingor induction eiementL will not send any current through the coils of the transmitting shunting. circuit which has amuch lower impedance than said coils. Also, this shunt acts as a short circuit, thereby allowing a bucking current to flow which will tend to prevent further change offluX and generation of an E. M. F.'in the kcoils of element L. In any event, there is not produced a current in the coils of the transmitting tra ck element T sufficient to affect the detecting element D and operate relay R, so that the train may pass without receiving a stopping influence. 1

Structure of Fig. .t- Tn Fig. 3 there has au.' i

been illustrated Va modified form of train connected in series and `disposed crosswise ofthe vehicle, and two receiving or detecting elements D and DEL disposed lengthwise of the vehicle and mounted on the outside of Y the track rails, have been provided instead of one such unit disposed between the track rails as illustrated in the'first embodiment of the invention shown in Figs. 1 and 2.

The circuits connecting the devices constituting the car equipment are the same as shown and described in connection with Fig. 2, the only dierence being that two field elements F and Fa, and two receiving elements D and DE1 are employed instead of the single elements illustrated in Fig. 2.

The track elements L and T, constructed the saine as sho-wn in Figs. 1 and 2, are also duplicated and are vdisposed crosswise between the track rails and lengthwise outside of thetrack rails, respectively, the disposition of the several cooperating elements on the canand track'being ofcourse selectedv so that these respective elements pass directly over one another.

' liith respect to the modified trackway circuits for checking the closed loop including the coils of the track velements L and T, it will be understood that the track rails l are divided by joints 2 into blocks in the same way'as in Fig. l, and that each of these blocks is provided with a track circuit including a track battery 3 and track relay 4:, a signal S, a line relay 1l governed in the saine Yway as the line'relay kshown in Fig. l, the control circuit for this linerelay being` omitted, however, in Fig. 3 to simplify the illustration.

The 45 degree and 90 degree control circuits element T, such current going through the 4 is connected directly to the battery, rather www dal l than through thev circuit controller 7-8,.or the armatures of the checking relays 18 and 19. The way in which the several signals are caused to assume the stop, caution, and clear positions as trains travel over the track will be readily und-erstood from analogy to the explanation in connection with Fig. 1; and since these features are the same, only the track equipment at the entrance to block T has been shown in Fig. 3.

Gperated by the signal S are two circuit controllers 56 and 57 which are shown in accordance with the same convention as those illustrated in Fig. 1 and previouslfy7 described. The circuit controller 56 is closed through a suitable angle between the 90 degree position and near the degree position, for example, from degrees to 90 degrees. The other circuit controller 57 is closed between the zero degree position of the semaphore and a position slightly above the l5 degree position, either the same or a few degrees more than the point at which the circuit controller 56 is closed, so that circuit controller 57 closes before circuit controller 56' opens, and vice versa.

Operation of Fig. 3,-Tn this modified arrangement, the integrity of the loop circuit for the track elements L and T is checked by making this loop circuit a. part of the track circuit for the next block in the rear, so that if there is a break in this loop circuit, the track relay of said block in the rear can not pick up, thereby putting at stop and caution, respectively, two signals and their associated track element-s in the rear of the defective track elements. In connection with this modiiied checking scheme, there is preferably employed an additional insulated joint 58 in one of the track rails at a short distance from the joints 2 at the exit end of the block, this distance being such that a pair of wheels of the car will be between the `joints 2 and 58 at the time the car elements F and D come over the track elements L and T.

vWhen the signal S is in clear position and circuit controller 56 is closed,'the track battery 3 of the block H supplies current to the track relay of that block over the following circuit :*Commencing at one terminal of the track battery 3, wire 59, coils 17 of track element La, wire 60, coils V17 of track element L. wires 61 and 62, circuit controller 56, wires 63 and 64:, track rail 1, back through the track relay of block H (not shown), back along the other track rail 1 to insulated joint 58, thence along wire 65, through adjustable resistance 66, wire 67, balancing resistance 68, wire 69, to the other side of the oint 58, short track rail section and wire70, back to the other terminal of battery 3.

VThe adjustable resistance 66 in this circuit just traced corresponds to the limiting resistance commonly used in connection with the track battery of track circuits, more par-V ticula-rly when such -batteries arefof the potash type or the like, and have low internal resistances, the function and purpose of such limit-ing r-esistance being well recognized in the'art and requiring no discussion in connection with this invention. Itis noted here that the adjustable resistance 66 may be omitted under certain conditions in practice, since the coils 17 of the elements L and La included in series with the track battery 3 may be utilized to serve the purpose of such limiting resistance. The other balancing resistance 68 is made equal to t-he combined resistances of the coils 17 of the trackelements T and Ta, for reasons that will be pointed out later.

From the foregoing it will be observed that the coils 17 of the elements L and La are included in the circuit bywhich current is normally supplied to the track relay of the block H, so that if there is a break at any time in these coils, or the wires connecting them, this track relay drops, the signal at the entrance to block H goes to stop, and the next signal in the rear is put to caution. In other words, so far as the coils of the elements L and La are concerned, this modified checking arrangement provides a continuouscheck or detection.

With this explanation ofthe normal condition of the parts and circuits of the trackway equipment of Fig. 3, assume now that a train, equipped as shown in Fig. 3, is in the block H, as shown, and is traveling in the normal direction of traliic indicated by the arrow, and suppose that the Y block I and also the next block in advance thereof (not shown) are clear or unoccupied. In the first place, the train inv question in the block H causes dropping of the track relay of that block in the usual way, the inclusion of the coils 17 of the track elements L and La in the track circuit for this block not modifyf ing in any way its usual and well recognized operation. vAs the train in question advances, and the first pair of wheels passes beyond the insulated joint 58, the resistances 66 and 68 are cut out. When the field' elements F and Fn on the car pass over the in- A duction elements L and La on the track, an

through the shunt provided by wires 62 and :i

63 and thel circuit controller 56, rather than through the coils of the transmit-ting elements T and Ta, the resistance of such shunt being of course much less-than that ofthe coils of said transmitting elements. quently, the transmitting elements T and Ta do not create a magnetic field to influence the receiving elements D and Da on the car. Also, the current iiowing in thecoils ofthe Conseinduction elements Land La throughmthe iii.

Levites lovv resistance shunt provided by the circuit controller 56 and associated Wires, acts in accordance With Well-known laws to lset up counter-magneto-inotive-forcel opposing the passage of iuX from the field elements F and FEl through the cores of said induction elements. In other Words, not only is the iioW of current through the transmitting elements T and Ta prevented, but also the inc duced current in the coils of the induction elements is reduced on account of the chok-v ing .effect caused by including these coils in a closed circuit of lovv resistance. In any event, the receiving elements D and DEL are not affected under the clear trai'iic conditions assumed.

Assume noW that the train in question advances Wholly into the block I. The signal S is caused to assume a stop position, the circuit controller 56 is opened, and the'circuit controller 57 is closed. The circuit over which the track battery 3 now delivers current to the track circuit in the block l-I is as follows Commencing at one terminal of battery 3, Wire 59, coils 17 of element La, Wire 60, coils 17 of element L, Wires 61 and 71, coils 17 of element Ta, Wire 72, coils 17 of element T, Wires 73 and 64, track rail 1, through track relay, back over other track rail, Wire 65, adjustable resistance 66, Wires 67 and 74C, circuit controller 57 closed, Wires 75 and 69, short track rail section and Wire 70, back to the battery 3.

It Will be noted that this circuit just traced includes the coils 17 of both the induction elements L and La and the transmitting elements T and Ta; or in other Words, the track battery 3 must send its current through the same loop circuit connecting said `induction and transmitting elements and placing them in condition to influence the apparatus on a passing train. In this Way, the integrity of the loop circuit, on which the `stopping operation of this particular type of 'system depends, is automatically checked;

and in case there is a break in the coils or their connecting Wires, no current VWill be supplied to the track relay of block H, putting the signal and associated track elements at the entrance to that block at stop, and also the signal next in the rear at caution, With its associated track elements also in the stopping condition. Consequently, in case of failure of the loop circuit following trains are controlled on the side of safety in the same Way as previously explained.

It will also be noted that in the circuit just traced, While the coils 17 of the transmitting elements T and Ta have been included in the track circuit, the balancing resistance 68 has been shunted out by closure of circuit controller 57, so that the net resistance in circuit With the track battery 3 remains the same, and the operating characteristics of the track circuit are not altered.

Suppose now that the train in question ad'- vances into the block J (not shown) neXt in advance of the block I. The signal S is operated to the 45 degree or caution position,

vbut the circuit controller 57 remains closed,

and the circuit controller 56 is open, so that there is no change in the circuits associated with the track .elements of the train control system. A

VJ hen the signal S is in either the stop or the caution position, circuit controller 56 being open, the coils of the transmitting elements T and Ta andthe induction elements L and La are connected in series in a loop circuit corresponding to the loop circuit hereinbefore discussed in connection With Fig. 1. The-loop circuit in Fig. 8, however,

includes the track battery 3, and also the` limiting resistance 66, if used, but the ref that the limiting resistance 66 is out out ofW the loop circuit, this loop circuit novv including only the track battery 3 and the connecting Wires in addition to the coils 17 of the j induction and transmitting elements. A stopping iniiuence is produced on the passing car under these conditions in the same Way as previously explained. The field elements F and Fa induce a current in the coils of the induction elements L and La which passes through the coils of the transmitting elements T and Ta and creates fields of flux which act upon the receiving elements D and D to cause deenergization of the relay R and the train control device K.

In connection With the operation of the modified arrangement shown in Fig. 3, it Will be noted that, When the track elements are in the activestopping condition the transmitting elements Tand Ta are inagnetized to a degree by current fromthe track bat-`l tery 3; and to utilize to the best advantage this energization of said coils that exists independently of the induction of current from the source of flux carried on the car, the lseveral coils and connectionsV are preferably se,

lected so that the first half Wave produced in the coils of the induction elements L and La is in a direction to assist the voltage of battery 3 to send current 'through the coils of the transmitting elements T and Ta, the car equipment. being correspondinglyl designed to employ this, first half Wave to drop the relay. It should be understood, however, that other combinations of connections may be employed, if desired.

lith regard to the checking operation of the modification of Fig. 3, it Will be noted that failure of the coils of the induction elements L and La at any time Will be maniliz@` the track circuit, so that there Vmay-be a failure of these coils atcertain times without causing stopping of the next train but it will be observed that, so long as there is a train in the block I, for example, or in the .next

l@ block in advance thereof, the integrity ofthey loop circuit through the coils of the transmitting elements T and Tais checked, and in case of failure, following trains will be slowed down or stopped. Thus, the complete loop 1E circuit is always under check at the time it may be needed to protect a train in the corresponding block or theneXt block in ad- Vance; and although the modified checking arrangement differs from that shown in Fig.

29T 1, since it does not leavesignals permanently in the stopping condition in case of failure,

each and every train will-be slowed down and stopped 1n case there is a train needing the protection of track elements that have a de- 25 fective loop circuit.

Structure of F ig. fa-In Fig. l another modified form of the car apparatus illustrated in Fig. 2 has been shown. The main difference between this forni and that of Fig.

3,92 is the omission of the thermionic amplifier, and the relay R is controlled directly from the coils of the receiving element D. The other car-carried devices are the same as those heretofore described and are placed @i substantially the same as those in Fig. 2, with `'the exception of the batteries. In Fig. 4 one battery C1 is used for the circuit through thercoils 55 of the receiving element, and another battery B1 for the coils 53 of the field felement. The circuitfthrough the vcoils 55 of `the receiving element Dmay be traced as follows z-Beginning at the battery C1, wire 76, winding of control relay R, wire 77, coils 55 of the receiving car element, and wire 78, back 4Q to the battery. The circuit through the coils "'53 of the field element F maybe traced as follows Beginning at the battery B1, wire 79, coils 53 of the iield element, wire 80, front contact 54 of the control relay R, wire 81,

5winding of the train control device K, and

` wire 82, back to the battery. The operation of this form of the invention is analogous to that illustrated in Fig. 2 and detail description is believed unnecessary.

55 'Structure of Fig. 5.-In Fig. 5 rhas been il- 'lustrated another form of car apparatus. The field element F and the circuit through its windings 53 is identical to that illustrated in Fig. 4 and is given like reference charac- 60., ters. The receiving element D1 ofthis modi- 'fied construction comprises two flux collect@ ing members or poles 83-84, having enlarged pole pieces. These enlarged pole pieces are arranged to be in communicating .relation 05 with the two pole pieces of a transmitting track: element-T as heretoforeY described. The upperendsr'of said members 83 and 84e are separated by an airzgap and pivotally mountedon the member 83 and disposed to bridge this air gap is a soft iron armature 85 biased to an open position by a spring 86. This armature 85 carries an insulated contact spring 87, which, under normal conditions, bridges stationary contacts (shown conventionally asarrows) to close the following circuit Beginning at the battery C1, wire 88, windingof control relay f-,wire 89, stationary contacts and contact spring 87, and wire 90,. back 'to the battery.

Operation of F 5.Assume a train, equipped with the car-carried apparatus illustrated in Fig. 5, is moving between two control points of a track'equipped with track devices as illustrated in Fig. 2 of the drawings. Under these conditions, the control relay R, the train control vdevice K, and the coils 53 of the field element F areenergized. vWhen the train passes over the track elements L and T illustrated in Fig. 2 in theiractive stopping condition, a current is caused to iow in theY loop circuit connecting the track elements Land T, in the same way as before described, thus creating a'iield of flux above the sending ortransmitting track element T which passes through the car-carried receiving or detecting elementDl, thereby attracting the armature 85 and opening the circuit to the control relay R, which in turn drops its armature 54 and breaks the circuit through the train cont-rol device K, bringing the train to a stop or imposing some other form of train control.

Structure of F ig; 6..-In Fig. 6 there has been illustrated. still another form of carcarried apparatus. In. this form the coils 53 ofy the fieldelement F are 'energized by a battery B1 in series withthe train control def vice K, in substantial-ly the same manner as illustrated in Figs. Lland 5. This circuit can befreadily traced on the drawings.

,The'receiving or detecting element D2 of this embodimentcomprises a core of general H-shape, the bottom legs being provided with enlarged pole pieces,-while the top legs have' inwardly extending projections. On the cross bar9l of said core is a coil 92 which is con- Stantlyenergized from a Vbattery or other source of current 93, soas to make one leg a north andthe ,otherY asouth pole of a inagnet, as indicated, for example, in Fig. 6. To one of these inwardly projections at the upper part` of said core is pivotally supported an armature ,94.which -is normally attracted in opposition to aspring by themagnetism passing through the crossbar, projections and thearinature. .A contact finger 96 is mechanically connected to but insulated from the armatureby insulated studs; and when the armature 94 is-in its normal attracted position,lthis' contact fingerv bridges a pair of 93 are selected and proportioned, with due regardv to the reluctance of the magnetic circuits under normal conditions, so that the ux produced by this coil and passing through the armature 94 Will be vapproximately that required to hold the armature in its attracted position against residual stops (not shown) in opposition to the spring 95 with a suitable margin to avoid premature opening of the armature due to vibration or the influence of track rails or other magnetic bodies along the track. @ther factors determining the magneto-motiveforce to be exerted by the coil 92 should, liovvever, be taken into consideration in practice,

`as will be evident as the vfunction and mode of operation of this form of car apparatus is further explained. It is noted here that the cross section of the cross bar 91 is selected so that this bar will be magnetically saturated by the flux produced by the coil 92, so that in case of a change in the reluctance of the partial magnetic circuits supplied with flux from the coil 92, the total amount of flux Will not materially increase and will divide itself in accordance with the reluctance of these magnetic circuits, as more fully explained hereinafter.

Operation of (J2-Assume the track equipment illustrated in Fig. 2 of the drawings to be in its danger condition, that is, with the coils of the track elements L and T in a closed and` unshunted circuit; and further that a car, equipped With the apparatus illustrated in Fig. 6 in its normal con- -dition illustrated is approaching the track elements L and T of Fig. 2 in this danger condition.

.As the car elements F and D2 pass over the track elements L and T, a current Will be set jup in the loop circuit by the change of flux produced in the coils 17 of the induction element L` When the field element F passes thereover.

The E. M. F. induced in the coils 17 of the induction element L will be one alternating cycle, one Wave or half cycle being in one direction, and the other Wave in the other direction. This induced voltage in turn sends a current through the coils 17 of the trans- 'mitting track element T (Fig. 2), and this S alternately north and south. As the receivn ing or detecting element D2 of Fig. 6 passes through this magnetic field, the magnetomotive-force produced by said transmitting element may assist or oppose that of the energized coil 92. If the magneto-motive-force of the transmitting element and that pro` duced by the coil 92 of the receiving element act together, some of the flux normally passing through the armature 94 Will be diverted through the core of the transmitting element. On the other hand, if the magneto-motiveforce of the transmitting track element opposes that of the energizedcoil 92, they both act together to send more flux through the armature 941 and hold it more strongl in its normal attracted position.

The several part-s are selected and proportioned so that the flux through the armature 94ris reduced suciently to allow the spring 95 to move said armature away from the attracted position and interrupt the circuit through the train control device K at the time these magneto-motive-forces are acting in the same direction. ln this connection it should be remembered that the cross bar 91 is made of such cross section as to be substantially saturated by theV flux produced by the energizing coil 92. Consequently, the transmitting track element T, With its assisting magneto-motive-force, when it comes into communication with the partial magnetic circuit through the cross bar 91 and lower legs of the element D2, necessarily causes a reduction in flux through the armature 9d, because the cross bar 91, being saturated, does not allovv any more than a certain sum total of Eux to pass, With the result that when part of this fiux is carried down through the track element, such flux is taken out of the armature.

The spacing of the field element F and the receiving element D2 on the car, with relation to the spacing of the induction element L and transmitting element T on the track, may be selected such that the legs of the receiving element D2 are directly over the pole pieces of the transmitting element T at the instant when the magneto-motive-force or fiux of said transmitting element is at a maximum in one direction or vthe other, or at any point between. Also, this relative spacing may be such that the receiving element D2 Will come over the transmitting element T at the time of one Wave, either .the first or second Wave of complete cycle, and Will be beyond the influence of said transmitting element for the other Wave of such cycle. The spacing of the car elements may, therefore, be selected or adjusted to obtain the mostadvantageous efiiect for the operation of the armature 94 to conform with any particular Working conditions. lt is .considered preferable to have this spacing such that the receiving element D2 will be under the influence of only one Wave Which isthe operating Wave, that is, the one that causes a diversion of fiux from the armature 9e through the transmitting track element.

@ne important characteristic of the modilee flux normally passing'throughthe armature 94 may be reduced by the action of the transmitting element T to a greater extent under ordinary conditions than could be obtained by merely changing reluctance by a track element constituting an inert mass of iron. In the arrangement of vthis invention, the magneto-motive-force momentarily created by the transmitting element T acts to pull or suck down, so to speak, the flux produced by the energized winding 92, and taking away a large proportion, if not substantially all, of the flux that this energized coil normally sends through said armature. Bridging the pole pieces of the receiving element D2 by a magnetic body, however, would merely serve to lower the reluctance ofthe partial circuit through the lower legs, and while this arrangement would deprive the armature 94 of some of its flux, there would still be ordinarily an appreciable amount of flux hrough this armature, inasmuch as the iux would divide inversely in proportion to the reluctance of the two multiple circuits set up. Structure of Fig. P-ln Fig. 7 there has been illustrated a form of car-carried apparatus for controlling the movement of a train, which embodies a modified form of field or primary devices which, although applicable to each oi the foregoing car-carried systems,

has for convenience been illustrated in Connection with the particular system shown in Fig. 4. Since the wiring diagram and the general arrangement of devices is the same as that of Fig. 4c, the same reference characters have been used for corresponding parts. Instead of a single fieldv element' F, two such elements have been provided. These elements F and F1 are supported on a vehicle in a manner to first induce a field of flux in one direction in an induction track element L, and then in the other in a manner that the flux will change rapidly from a maximum in one direction to a maximum in the other direction, whereby a current is in-k duced in the loop circuit track devices of a much greater effective value than Yif only one field element is used. Although these field elements may be disposed in any relation to t-he trackway as illustrated by the cooperating induction track element that has been illustrated in each of Figs. 8 to 17, they have for convenience been shown disposed crosswise of the vehicle. The iield elements F and `Fl are provided with coils which are conv AOperation of Fig. 7.-Assume that lthe trackway devices illustrated in Fig. 2 are in the danger condition, that is, the line relay 11 is deenergized, thus opening the shunt cirn lto a certain maximum value from the time the field element F gets into the range of action, to the time it gets directly over the induction element, thus generating a voltage in the winding of the induction element L as illustrated by the waveX in Fig. 'l1-A. At this position of 'the field element, that is, when it is directly over the track element, very little leakage of flux between the eld elements F and F1 is present. As the field element F recedes from the induction element L the flux through the induction element decreases to zero very rapidly.Y This is believed to be due to the increase of reluctance through the magnetic circuit comprising the elements F and L, aided by the increase of leakage between the field elements, while the field elements straddle the induction element. This leakage, or diversion of flux, from the core of the induction element L is assisted by the fact that the alternative path through the field element F1 includes a helping source of magneto-motive-i'orce, the legs of said field elements being of opposite polarity as previously explained. This rapid decrease of flux produces a voltage in the opposite direction to that of the first wave X, for reasons well-known to those skilled in theart.

At the point of movement when the field elements are spaced equal distances from the induction element L, the field of flux through the induction element is substantially Zero, but `the voltage generated at this point is not necessarily zero, since the rate of change of flux at this point may be high, and in passing through this point the flux changes in direction since the legs of the field elements F and F1 are of' opposite magnetic polarity. Consequently, there is the greatest rate of change of liux this point, and the induced E. M. F. 1s a maximum.

As the vehicle advances from the point just" mentioned, the flux through the induction element increases in the opposite direction until the ield element F comes directly over the induction element L, at which point the flux through the element L is a maximum, the rate of change small and the voltage low. This completes the lower wave Y of the voltage curve shown in Fig. T-A. As the ield element F:L recedes from the trackrelement L the flux through the track element gradually lie changes to zero, making the wave Z in Fig.

Fig. 7-A is intended purely for purposes of explanation, to illustrate how the lower voltage wave Y, which is generated by the combined action, so to speak, of the two field elements F and *l has a higher maximtun value. It should be understood, however, that the wave forms are merely illustrative and are not intended to be quantitatively accurate, it being readily appreciated that the exact values of induced voltage will in practice vary considerably, depending upon the size of parts and other features of design, together with a number of other variable factors.

It should also be understood that the foregoing explanation of mode of operation is based upon theoretical assumptions, which may or may not be .invariably true in the practical application of the invention, on account of variations of design and -other conditions.

Besides the advantage of generating a much larger current in the track loop circuit by the employment of two field elements instead of one, a stillother desirable characteristic is present. If a single field element isy carried crosswise of the vehicle and is energized by a direct current, there is a tendency for it to permanently magnetize crossing rails and similar magnetic bodies which have sufficient permanence (hold their magnetism) and when such field element repeatedly passes over such bodies, they will become permanent magnets. These magnetized bodies or crossing rails may under certain adverse circumstances cause a false control influence to be transmitted to the detecting element. If two field elements trailing each other having their polarities opposite are used, as has ust been illustrated, any residual magnetism set up by the passage of one of the field elements will be killed by the passage of the other field element, and the maximum magnetism Vthat will be set up at any time will be the residual magnetism left by the passage of a single element. Such residual will be very feeble and thus harmless, as compared with the Vmag` netism produced when a single field element passes over such bodies repeatedly.

@E @cking of car-Cameri (Ze/vicesf-It should be noted that every car-carried equipment illustrated is constructed along the normally closed circuit principle, cris self-checking. In Figs. 2 and 8 the failure of a sufficient current supply to the filament 50 ofthe audion will reduce the plate current which in turn will drop the armature of the control relay R. and stop the train as heretofore explained. The saine is true of insufficient potential on the `grid circuit. If either the circuit through the control relay It. or the circuit through the train control device K should be reduced or interrupted altogether, the train will be stopped or otherwise controlled. In Fig. 6,if

the current in the winding 92 on the cross bar 91 should be sufficiently reduced or altogether interrupted, the armature 94C will be pulled away from the extending projections by the spring 95, thereby opening the circuit to the train control device K and applying the brakes or controlling the train in some other suitable manner.

Disposition of mais elements-On account of certain variable conditionsysuch as the variation in the diameter of the car wheels due to wear, and other varia-ble quantities en-V rails, other clearance factors enter into thel problem and larger air gaps must in some cases be provided. For instance, if the track elements are placed between the rails, certain' railroads require themto be placed several inches below the top of the'frail, in `order that they. Will clear the Hangers ofV snow plows which extend down below the topjof thejrails. Certain of these railroads will, however, permit these track'elements to be placed level with the track if their poles are substantially in the middle between the rails, becausethe snow plow flangers may be notched at this point to Vclear the track elements and still take out as much snow from betwen the rails as is necessary. A f

In connection with these devices still another questionmust be taken into consideration, namely, the spacing of the car-carriedv elements with respect to the spacing of the trackway elements, which should be such that the impulse received by the detecting element will be the strongest, allother conditions remaining the same. In this connection it should be noted'that in each inductive type of car apparatus,shown in Figs. 2, 3, 4 and 7,v the rate of change of flux in thel detecting element D is dependent lon both the rate of change of flux in the transmitting element T and the velocity at whichy the element D passes over the element T. The detecting elements D1 and D2shown inFigs. 5 and 6, depend on the amount of flux rather than on the rate of'change of flux, and thereforethe car and track elements are so spaced relatively that the flux produced by the transmitting element T will be mosteffective whenthe detecting elementD is directly over the same.

Still another condition regarding the spac-4 ing of the car lelements with respect to the track elements must be taken into consideration, especially in regard tothe car-carried devices illustrated in Fig. 6.' In this form of Y detecting element, the operation does not depend merely on the amount of flux,but.also

' D? will vbe over the transmitting element 'I when-the flux induced therein is most effective and also in the proper direction. If two field elements, as illustrated in Fig. 7, are employedin connection with anyone of the `lcar-carried systems illustrated, a still further consideration must be given to the relative spacing of car and track elements. In this event, the elements will be so spaced that the magnetism due to the largest wave of the curve X, Y, Z willbe in the proper relation to the detecting element I), such relation to the moving detecting element depending upon whether the particular detectingV element is responsive to rate of change of flux or to the amount .of flux, as heretofore explained.

In each ofthe Figs. 8 to 17, inclusive, an arrangement or disposition of the track elements has been illustrated to show howr they may be arranged to suit particular operating conditions. vTwo track rails 97 and 98 have been shown with respect to which an inductive or generating element L and a transmitting or sending element T has been illustrated. Certain of these elements have been designated T and L on-the drawings; butit should bev understood that either Aelement may be used for either function. Although various arrangements of placing of the track elements with respect to thel track rails have been illustrated, it should be'horne in mind that these are merely illustrative, and that all possible arrangements have not been shown. Since these figures are self-explanatory, no

further description thereof is believed necestransmitting this control influence, the failure` of which mightprevent the transmission of aninfluence at a time when `one is to be transmitted,vif desired, a' checking system to check the integrity of the circuit may be added; and several forms of such a checking system have been provided.

W'hile I hav-e explained the'nature of my invention by discussing the construction and inodeof operation of certain specific forms of-apparatus, it will be evident that the inventioii may be considered in the broaderas pect of a novel method of transmitting influences from th-e trackway to moving vehicles, adaptable to train control systems.

While I have described my invention in connection with a specific type of block sig-A nal system, the invention is more general in its application. The particular construction shown and described may be modified and adapted in manyl respects to suit the particular working conditions; and I desire t0' plate circuit, a grid circuit, a filament circuit,

an electro-'responsive device connected in saidplate circuit, an influence receiving coil con-- nected in said grid circuit, a. magnetic core having a normally energized winding theref on for producing a magnetic yflux in said core; and' of trackway apparatus' including a pair ofk trackway elements each having a coil there# on and so positionedwith respect to the track-V way that one element cooperates with saidv influence receiving element when the other cooperates with said Eux producing coil, and a circuit connecting the coils of said track# way elements in series when a control infin-- ence should he transmitted.

2. Trackwayapparatus for communicating control influences from one car-carried device to another under predetermined traffic conditions ahead comprising, a pair of cores each having two upstanding legs and disposed along the trackway so that the legs extend upwardly, a coil on each of said cores, and' means for effectively connecting said coils in series under predetermined traffic conditions ahead, said cores being positioned along the ics trackway so that the legs ofeacli of said cores fall in different planes.

' Trackway apparatus for cominunicating control influences from one car-carried device to another under predetermined traffic conditions ahead comprising, a pair of cores each having two-upstanding legs and disposed alcng the trackway so that the legs extend upwardly, a coil on each of said cores, and' means for effectively connecting said coils in series under predetermined traffic conditions ahead, said cores being positioned in different Ypaths along the trackway and being so placed in the plane of the trackway that the legs of each of said elements are disposed in different vertical planes.

*4. In an automatic train control system, the combination of car-carried train control devices, a track device including a deenergized closed circuit for communicating control influences to said car-carried devices,

isc

CTI

one of said car-carried devices inducing a voltage in said circuit upon passage of said car-carried devices over said trackway ldevices, and the other of said car-carried devices detecting the lioW of current in said circuit, and means for checking the integrity ot said circuit by each passing train to safeguard a following train.

5. In an automatic train control system, a pair of track devices each including a core having a coil thereon, said coils being connected by a local closed circuit for transmitting a danger control influence to a moving train, and means for transmitting a danger control influence to the track device at the next control point in the rear it' the continuity of the circuit is interrupted.

6, In an automatic train control system; the combination of a trackvvay divided into blocks by insulating joints, a signal at the entrance to each block, influence communicating means at the entranceto each block for transmitting inductive control influences t0 a moving' vehicle and including a coil, means for preventing said signal from assuming the proceed position when the circuit including the coil of said influence communicating means is open; and car-carried apparatus controlled in accordance With Whether the circuit including` said coil is open or closed.

'74A system for transmitting controlling influences from the trackvvay to moving vehicles, in which a'tluX responsive detecting device on the vehicle is actuated by cooperating means partly on the vehicle and partly on the track and including a source of magneto-motive-force on the vehicle, said source of magnetic-motive-force and said detecting device having differently disposed liuX paths` with relation to the trackvvay.

8. Trackway apparatusv for automatic train control systems comprising, a railway track divided into blocks, an inductive influence communicating element tor communicating inductive control in'liuences from the trackivay to a vehicle including a core of magnetic material having a Winding thereon at the entrance to each block, a Wayside signal located near the entrance to each block for indicating traiic conditions ahead, a circuit including said Winding closed under predetermined traffic conditions ahead, and mea-ns for preventing said signal from assuming the proceed position when said circuit is open. y

9. In a train control system of the character described, a linx responsive device on the vehicle, a source of magneto-motiveforce on the vehicle, and trackway means governed by said magneto-motive-torce :tor influencing said flux responsive device, said source and luX responsive device having iluX paths disposed differently With respect to the trackway.

l0. Trackivay apparatus for block signaling and train control systems comprising, an influence communicating track element for transmitting control iniiuences inductively from the trackWay to suitable vehicle carried influence receiving means including. a core having a coil thereon, a Wayside signal, a

relay, a circuit including said coil and said relay, and a circuit controlled by said relay for preventing said signal from assuming the proceed condition if the circuit including said coil andrelay is open at a time When it should be closed.

ll. TrackWay apparatus for block signaling and train control systems comprising, an

influence communicating track element for transmitting control influences inductively Jfrom the trackvvay to suitable Vehicle-carried influence receiving means including a core having a coil thereon, 'a Wayside signal, a circuit including said coil, and means for preventing said signa-l from assuming the proceed condition it the circuit including saidcoil is open.

12.-'I`rackWay apparatus for block signal-v ing and train control systems comprising;`

an iniuence communicating track elementV for transmitting control influences` inductively from the trackvvay to suitable vehicle carried influence receiving means including" a core having a'coil thereon, a Wayside signal; a circuit including said coil, a relay and a source of energy; a circuit for causingsaid signal to assume the proceed condition iiicludinga front Contact of said relay, Whereby said signal cannotV assume the proceed condition unless the circuit includingsaid coil is intact and said relay assumes its energized position. Y Y f 13. In an automatic train controlsystem; the combination of car-carried apparatus comprising, anormally energized inductive iniiuence transmitting element, an inductive influence receiving element of magnetic inaterial having an influence receiving coil thereon, a thermionic device connected to said iniuence receiving coil, an electro-responsive device connected to said thermionic device; and of trackway apparatus for inductively coupling said iniiuence transmitting element t0 said influence receiving element including trackWay devices eiiectively connected in series under predetermined traiic conditions ahead, and meansfor checking the integrity of the circuit including the tvvo tracktvay devices in series.

14. A train control system comprising, a car-carried magnetic element having a normally energized Winding thereon for'producing a magnetic linx in such element, another car-carried magnetic element. having an influence receivine` Winding thereon, track- `Way means including a circuit in Which curcondition to create a magnetic field inluencl ing the influence receiving winding, and means including a train control device andY electrical circuits for controlling the train when said influence receiving winding is influenced, said last mentioned means and said trackway means being constructed so that accidental interruption of any of said circuits will cause an actuation of said train control device. 15. Trackway apparatus for block signalingfand train control systems comprising; a railway track divided into blocks each having a track relay; an influence communicating track element for transmitting` control influences inductively from the trackway to suitable vehicle carried influence receiving means including a core having a coil thereon located at the entrance to each block; a wayside signal; a circuit including said coil, a check relay and a source of energy; a line relay controlled by said track relay; and a circuit for causing said signal to assume the proceed condition including a front contact of said check relay and a front contact of said line relay in series.

16. Trackway apparatus for automatic lock signal and train control systems comprising, an influence communicating track element for transmitting control influences inductively from the ltrackway to suitable vehicle carried iniiuence receiving means including va core having two coils thereon, a

' wayside signal, two circuitsin multiple each transmitting control influence to .said influence receiving coil including a track element of magnetic material having a coil thereon connected in series with the usual track circuit, and means for shunting said last mentioned coil under predetermined tralic conditions ahead. Y

18. A trackway apparatus for automatic block signaling and train control systems comprising, a railway track divided into blocks each having a closed track circuit, an inductive iniiuence communicating device including a core of magnetic material having a winding thereon located near the entrance to .60. each block, a wayside signal at the entrance to each block, and a control circuit for said signal, closed only if said winding is intact, for causing said signal to change its indication from stop to caution or proceed.

19. A train control system comprising, a

normally energized electro-responsiveA device, a normallyvenergized train control ape, pliance controlled by said device, a car-carried influence receiving element having a coil thereon in which a current flows to maintain said electro-responsive device energized, whereby the reception of a control influence causes deenergization of said device, anv influence transmitting element including a normally energized field coil connected in series with said train control appliance, and trackway apparatus for inductively coupling said' influence transmitting element to said influence receiving element under predeterminedv traffic conditions ahead.

20. A trackway apparatus for automatic block signaling and trainf control systems comprising, a railway' track divided into blocks each having a closed track circuit, an inductive influence communicating device including a core ofy magnetic material having a winding thereon located near the entrance to each block, a wayside signal at the' entrance to each block, and means effective only if current traverses said Winding for changing the indication ofsaid signal from stop to a more favorable indication after once caused to give its stop indication by the passage of a train.

21. Trackway apparatus for automatic train control systems of the type employing closed track circuits'each having a track re-, lay comprising, a trackway device including a core of magnetic material, a coil associatedV with said core, a wayside signal controlled by such track circuits to give indications corresponding to traffic conditions ahead, and means effective if said coil is accidentally' openecircuited to prevent said signal from again indicating favorable traiiic conditions regardless of actual trafc conditions existing ahead so long as said coil remains open circuited.

22. Trackway apparatus for automatic train control systems of the type employing closed track circuits each having a track relay comnrising, a trackway device includinga core of magnetic material, a coil associated with said core, a check vrelay inrseries with said coil, a source of energy for energizing said coil, a circuit'which if energized causes said signal to assume a favorable traffic indicating condition, said circuit including a front contact of said check relay and a source of energy, whereby said signal will indicate unfavorable trailic conditions regardless of actual traic conditions existing ahead if the continuity of said coil is accidentally broken and the signal has thereafter indicated adverse traific conditions. Y

23. Trackway apparatus for automatic train control systems of the type employing closed track circuits each having a track relay comprising; a trackway inductive influence communicating device including a core of magnetic material; a coil associated with 

